EMBDEN – Investigators are still trying to pinpoint the cause of a fire that destroyed a salmon hatchery and killed nearly 3 million juvenile fish, but believe the fire was an accident, an investigator said Monday.

Firefighters from seven towns battled the Thursday night fire at the Kennebec Hatchery of Atlantic Salmon of Maine. There were no injuries.

“We’re not getting any indications that would suggest that the fire was intentionally set. We’re trying at this point to determine ignition source,” said Sgt. Stu Jacobs, fire marshal investigations supervisor.

The fire started in the mechanical room on the second floor that contained the pumping system that supplied fresh water and oxygen to about 100 circular tanks holding the juvenile salmon. The salmon suffocated when the fire caused the electrical system to fail, cutting off oxygen to the freshwater tanks.

State Fire Marshals and state electrical inspectors are working jointly on the investigation. “We’re still pursuing information on the ignition source,” Jacobs said. The site examination is complete, he said.

The investigation could be completed within days after the electrical supervisor weighs in, he said. The Kennebec Hatchery contained 740,000 Atlantic salmon smelt ready for transfer to ocean pens, as well as 2.1 million Atlantic salmon fry that were to be stocked in pens this fall and next spring.

Atlantic Salmon, a subsidiary of Norwegian-owned Fjord Seafood, also operates a smaller hatchery in Oqussoc, near Rangeley.